1. Field of the Invention
Embodiments of the invention generally relate to the field of economizer valves, and more particularly to a pressure build economizer valve that opens based on increasing system pressure and does not have overlapping pressure build and economizer functions.
2. Discussion of Related Art
Economizer valves are used in industrial applications for pressure regulation in cryogenic liquid and gas supply systems. Pressure build economizer (PBE) valves combine pressure building and economizer functions into one unit. Existing PBE valves for cryogenic liquid cylinders and bulk tanks are based on three types of designs. The three types include: (1) an active economizer that overlaps the pressure build function, (2) an inactive orifice economizer function, and (3) an active economizer that flows through the pressure build shutoff piston. Existing PBE valves with active economizers that overlap the pressure build function undesirably reduce the pressure build capacity of the system until the cylinder pressure has dropped below normal operating pressures. Existing inactive economizer functions have a fixed orifice economizer such that the economizer function is always open, undesirably limiting the capacity of the pressure build function or the economizer orifice is too small to give adequate pressure reduction within a reasonable period of time. Existing PBE valves with active economizer functions that flow through the piston are costly to manufacture and also have a potential problem of leakage between the pressure build and economizer functions that can create runaway cylinder pressure.
It would, therefore, be an advantage to provide a cost effective economizer valve for cryogenic liquid cylinders that has an active economizer that opens based on increasing system pressure and does not have overlapping pressure build and economizer functions.